Trial of Chelation Therapy Shows Benefits, but Doubts Persist

Chelation therapy has been used as an alternative treatment for heart disease since the 1950s, but with scanty evidence to support the practice, most medical doctors have long dismissed it as little more than quackery.

But now a prestigious medical journal has published the results of a large, long-term clinical trial of chelation in heart disease patients. While critics were quick to point out the study’s myriad irregularities, the findings have dumbfounded cardiologists: The results suggest chelation, originally used to treat lead poisoning, just might help heart patients.

The benefits were modest: Heart attack patients older than 50 who underwent 40 chelation infusions had 18 percent fewer cardiovascular events in five years of follow-up than those given a placebo. The researchers had expected a drop of 25 percent, however, and their results barely reached statistical significance.

Chelation involves infusing patients over several weeks or months with a substance, usually calcium disodium EDTA, that binds heavy metals to help the body excrete toxic materials. The use of chelation to treat heart disease and other ailments is based largely on anecdotal experience, however, and the substance used in the new trial was disodium EDTA, which, unlike calcium disodium EDTA, is not approved by the Food and Drug Administration for this purpose.

“If you had asked any cardiologist, to a man or to a woman, they would have said this study would be negative, and that included me and my associates,” said Dr. Gervasio A. Lamas, a cardiologist at Columbia University and lead author of the new study. “But it wasn’t, and that’s the one thing we should be focusing on.”

So have scientists found an effective new treatment for heart disease? Critics like Dr. Steven E. Nissen, a Cleveland Clinic cardiologist, say no, questioning the trial’s methodology and reliability.

“The real danger is that these types of therapies divert patients away from what we know works, things that have been well studied, have a track record and are approved by the F.D.A.,” Dr. Nissen said. “I have had patients over the years who had severe coronary artery disease and needed bypass surgery, but they are scared of surgery and they go to the Web and find a chelationist who promises to ‘clean out’ their arteries, and they are sucked into this.”

The trial, which lasted over a decade and cost the government $31 million, was riddled with problems, critics say. Treatment involved 40 infusions over the course of a year. The goal was to enroll 2,372 patients, but only 1,708 were enrolled.

Among the trial sites were anti-aging and wellness centers that have long provided chelation and other unproven treatments, like high-dose vitamin C to cure cancer. The study was disrupted when complaints, including questions about the informed consent procedures, were lodged with the federal Department of Health and Human Services. Nearly 290 participants — one in every six — withdrew their consent; investigators lost track of 22 more.

The National Institutes of Health, which sponsored the study, examined the data repeatedly while the trial continued, something Dr. Nissen said was “unacceptable by any standard” because of the sponsor’s investment of money and prestige.

Dr. Gary H. Gibbons, director of the National Heart, Lung and Blood Institute, said in a statement that the institute had no commercial interest in the outcomes of the trials it funds. “N.I.H. had no bias for or against the therapy,” he said.

The number of Americans using chelation therapy has increased in recent years, though the treatment is grueling and expensive and can be dangerous. While critics worry that data from the new study was compromised, Dr. Eric Topol, a cardiologist with Scripps Health, said the medical community should pay attention.

“Even with all the warts of this trial, it does appear to signal a benefit,” he said. “That challenges the prevailing dogma.”

A version of this article appears in print on 04/16/2013, on page D5 of the NewYork edition with the headline: New Look At Therapy After Trial.